There is a flag that transforms the normal ability into a hidden one and like everything else this flag is fixed for an egg. Either you scout with Pokemon whose female has its HA; or you scout with your Magikarps first, reset, then switch them out for Pokemon whose female can pass its HA, then reset again. The latter method obviously takes longer, but if you do not bother with getting yourself new Magikarps (with HA), it will be a viable alternative.I just bred a 31/30/30/31/31/31 HP Ice Timid Helioptile w/Dry Skin using this method. I plan on breeding an HP Fire Timid Protean Froakie and an HP Grass Timid Litleo. How do I make sure I get Protean as the ability for Froakie? I'm currently using two magikarps as scouts.